Lift mechanism for a vacuum system

ABSTRACT

A vacuum lifter mountable on a fork lift has a low vertical profile particularly useful in the warehousing of sheet materials, minimizing the needed clearance thereabove to access the sheet materials. The lifter includes a low vertical profile frame having a protective wall to minimize damage to the vacuum cups mounted on the frame. The vacuum cups may be raised to a position within the protective wall and lowered to a position therebelow to facilitate vacuum attachment to sheet materials or other objects to be lifted. The vacuum cups may be mounted on the frame via pivot arms cantilevered from the frame. The pivot arms may be positioned in opposed pairs and raised by camming action such as by a cam bar extending between the pivot arms and slidably mounted on the frame.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to a vacuum lifting mechanism. More particularly, the invention relates to a vacuum lifter which is mountable on a forklift and has a low profile. Specifically, the invention relates to such a vacuum lifter which has a protective wall for protecting the vacuum cups of the lifter.

2. Background Information

Vacuum lifters are commonly used to pick up a wide variety of materials, including flat sheet materials such as steel, plastic or wood. Vacuum lift devices are commonly mounted on heavy equipment such as an arm on an excavator, suspended from overhead hoists or mounted on the forks of a fork lift. Depending on the specific configuration and degree of suction from a vacuum source, vacuum lifters may lift relatively light objects or objects that weigh hundreds or thousands of pounds.

In the warehousing of flat sheet materials and the like, vacuum lifters are commonly used with forklifts for stacking and removing the sheet materials from shelving at various heights. These vacuum lifters include a frame having mounted thereon vacuum cups which contact the sheet materials so that a vacuum subsequently applied via the vacuum cups to the sheet material allows the material to be lifted. The known prior art lifters are relatively bulky and have a rather large vertical profile which is commonly twelve inches or even more. As a result, there must be at least twelve inches of free space or clearance above the sheet material on a given shelf in order for the known vacuum lifters to be inserted therein for lifting the sheet material. Thus, for every shelf of sheet material, there must be twelve inches between the top sheet and the bottom of the shelf thereabove. This adds substantially to the amount of warehouse space required for the stacking of sheet materials. In addition, the known prior art vacuum lifters have vacuum cups which hang below the frame so that they are exposed to inadvertent damage during movement of the lifter into warehouse shelving and the like. Thus, there is a need in the art for a low profile vacuum lifter which is also capable of protecting the vacuum cups.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an apparatus for lifting flat material comprising: a frame; a pair of fork lift arm receivers on the frame; and at least one vacuum cup mounted on and movable relative to the frame between raised and lowered positions.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of the vacuum lifter of the present invention with the vacuum cups in the lowered position and the vacuum source shown diagrammatically in dashed lines.

FIG. 2 is a rear elevational view of the lifter with the vacuum cups in the lowered position showing the fork receiving tubes.

FIG. 3 is a top plan view of the vacuum lifter with the vacuum cups in the lowered position.

FIG. 4 is a sectional view taken on lines 4-4 of FIG. 3.

FIG. 5 is a top plan view of the lifter with the vacuum cups in the raised position.

FIG. 6 is a sectional view taken on lines 6-6 of FIG. 5.

FIG. 7 is a perspective view of the vacuum lifter with the central frame member removed to show the cam bar and the vacuum cups in the lowered position.

FIG. 8 is similar to FIG. 7 and shows the vacuum cups moved to the raised position in response to movement of the cam bar.

Similar numbers refer to similar parts throughout the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The vacuum lifter of the present invention is shown generally at 10 in FIGS. 1-3. Lifter 10 includes a rigid frame 12 and a plurality of vacuum cups 14 which are used to contact and apply a vacuum to sheet materials or other objects in order to lift said objects. Vacuum cups 14 are movable between a lowered position shown in FIGS. 1-4 and 7 and a raised position shown in FIGS. 5, 6 and 8.

Frame 12 has a front 16 and a rear 18 defining therebetween an axial direction, and first and second sides 20 and 22 defining therebetween a longitudinal direction. Frame 12 also has a top 17 and a bottom 19 defining uppermost and lowermost surfaces of frame 12. Top 17 and bottom 19 define therebetween a height H1 (FIG. 2) of frame 12 which is substantially less than that of the known prior art lifters. Typically, the height H1 is on the order of three to five inches. Frame 12 includes a perimeter wall 24 having an outer surface 26 defining an outer perimeter of wall 24 and frame 12, and an inner surface 28 defining an inner perimeter of wall 24. Perimeter wall 24 includes a longitudinally extending front wall 30 which extends nearly the entire length of frame 12. Wall 24 further includes a rear wall divided into first and second segments 32 and 34 which extend longitudinally and are spaced from one another and are aligned along a common vertical longitudinal plane. Each of segments 32 and 34 are roughly one third the length of frame 12 in the exemplary embodiment. Perimeter wall 24 also include four beveled corner walls 40A-D which connect the various other walls of wall 24 and are typically angled at approximately 45° relative to the other walls to eliminate a sharp 90° corner which may enhance the likelihood of property damage or personal injury.

A longitudinally extending central frame member includes first and second central walls 42 and 44 each of which extends between and is connected to side walls 36 and 38 respectively at the central axial positions thereof. Five axially elongated slots 45A-E are formed in each of central walls 42 and 44 although they are shown only in wall 42 in FIG. 1. Slots 45 are spaced longitudinally from one another so that the distance between each adjacent pair of slots 45 is roughly the same. First and second cross bars 46 and 48 extend axially between and are connected to first central wall 42 and front wall 30. First cross bar 46 is positioned about one third the longitudinal distance of frame 12 from first side 36. Likewise, second cross bar 48 is positioned about one third the longitudinal distance of frame 12 from second side 38. Thus, first and second cross bars 46 and 48 define therebetween approximately one third of the length of frame 12. All of the aforementioned walls and cross bars are preferably substantially flat and vertically oriented to provide a strong, yet relatively light weight frame although various configurations of frame 12 will be evident to one skilled in the art. In addition, rigid connections are formed at the intersections of the various walls of frame 12.

Lifter 10 further includes a forklift fork receiver assembly which is disposed partially within the perimeter of perimeter wall 24 and partially outside of perimeter wall in a rearward direction. More particularly, this assembly includes first and second axially extending fork arm receivers in the form of tubes 50 and 52. Each of tubes 50 and 52 is connected at the respective front end thereof to second central wall 44 and extends rearwardly therefrom. Tube 50 is connected adjacent its midpoint to a terminal end of first segment 32. Likewise, tube 52 is connected adjacent its midpoint to a terminal end of second segment 34. Each of tubes 50 and 52 extend rearwardly from segments 32 and 34 to rear ends in which are formed rearwardly opening entrance openings 54 of respective interior chambers 56 which extend the entire axial length of tubes 50 and 52. Interior chambers 56 are configured to receive respective fork lift arms via entrance openings 54 so that lifter 10 may be supported by a fork lift for the raising and lowering thereof. A tubular cross bar 58 extends axially between and is connected to each of tubes 50 and 52 rearwardly of segments 32 and 34. Each of tubes 50 and 52 and cross bar 58 has a top 60 and a bottom 62 defining therebetween a height H2 which is less than height H1. Thus, the receiver assembly including tubes 50 and 52 and cross bar 58 have a vertical profile which is completely within the vertical profile of frame 12. More particularly, top 60 of the fork lift receiver assembly is below top 17 of frame 12 and bottom 62 of the assembly is above bottom 19 of frame 12 so that no portion of the fork lift receiver assembly is disposed above or below frame 12.

Lifter 10 includes a vacuum system which includes vacuum cups 14 and a vacuum source 64 which is preferably battery powered by an onboard battery to provide a vacuum or suction to cups 14 via vacuum conduits 66A and B. More particularly, vacuum conduit 66A is connected to source 64 and communicates with conduits 66B connected to each of vacuum cups 14 (only one conduit 66B being shown for clarity). Each vacuum cup 14 includes a rigid upper member 68 having formed in an upper wall thereof a port 70 to which a respective conduit 66B is connected. Each vacuum cup 14 also includes a lower flexible suction cup 72 typically formed of rubber or a polymeric material. Each suction cup 72 has an annular lower attachment surface 74 which is substantially horizontal and configured to contact and attach to sheet material or other object which is to be picked up via the vacuum of lifter 10.

As previously noted, each vacuum cup is movable between raised and lowered positions. More particularly, each of vacuum cups 14 is mounted adjacent a free end 76 of an arm 78 which is cantilevered from one of central walls 42 and 44. A plurality of mounting brackets 80 are mounted on walls 42 and 44 with each arm 78 pivotally mounted thereon via a pivot 82. Each mounting bracket 80 includes a pair of axially spaced flat plates which define a space therebetween for receiving the inner end of each arm 78. Each arm 78 has an inner end 84 which at a point below pivot 82 serves as a cam follower. As shown in FIG. 5, each vacuum cup 14 and arm 78 is circumscribed by various walls of frame 12 and/or by portions of the forklift receiving assembly. For instance, a pair of arms 78 and the vacuum cups 14 attached thereto are circumscribed by cross bar 46, a portion of first central wall 42, a forward portion of side wall 36 and a portion of front wall 30. Another of arms 78 and the vacuum cup 14 mounted thereon is circumscribed by cross bars 46 and 48, a central segment of first central wall 42 and a central segment of front wall 30. Yet another arm 78 and vacuum cup 14 are circumscribed by a central segment of second central wall 44, forward portions of forklift tubes 50 and 52, and cross bar 58. The remainder of arms 78 and vacuum cups 14 are likewise surrounded by various walls of frame 12 and/or portions of the forklift receiver assembly which will be evident upon review of the figures.

A plurality of cams in the form of wings or ramps 86 extend from between walls 42 and 44 respectively through slots 45 and include tapered cam surfaces 88 which provide a camming engagement with cam followers 84 when ramps 86 move longitudinally. More particularly, ramps 86 are carried by and extend outwardly from a longitudinally elongated cam bar 90 (FIG. 7) which extends nearly the entire length of frame 12 between central walls 42 and 44. Preferably, cam bar 90 and ramps 86 are formed as an integral one-piece member. As shown in FIG. 7, each pair of ramps 86 which are opposite one another and the portion of cam bar 90 to the right thereof forms an arrow shaped configuration.

An actuator 92 is pivotally mounted on a mounting bracket 94 which is rigidly attached to second central wall 44. Actuator 92 includes an actuating arm 96 such as the piston of a piston cylinder combination which is pivotally mounted on a mounting plate 98 which extends rearwardly from cam bar 90 and extends through slot 45A and central wall 44 along with one of ramps 86. Actuator 92 may be powered by any suitable source including vacuum source 64. Cam bar 90 is thus slidably mounted between walls 42 and 44 with ramps 86 slidably received within respective slots 45 and axially moveable in response to movement of actuating arm 96.

In keeping with maintaining a minimal vertical profile and with reference to FIGS. 4 and 6, pivot arms 78 are configured to stay within the vertical profile of perimeter wall 24 in the lowered position of FIG. 4 and the raised position of FIG. 6. Pivot arms 78 have a triangular configuration which allow arms 78 to stay within this vertical profile. More particularly, each pivot arm 78 has a height adjacent inner end 84 which is greater than that of pivot arm 78 adjacent outer or free end 76. Each pivot arm 78 has a top surface 100 and a bottom surface 102 each of which are straight and axially elongated. As shown in FIG. 4, bottom surface 102 in the lowered position is substantially horizontal and disposed closely adjacent bottom 19 of perimeter wall 24, and top surface 100 angles downwardly and axially away from central walls 42 and 44. Thus, in the lowered position, top surface 100 adjacent inner end 84 is closely adjacent top 17 of perimeter wall 24 and top surface 100 adjacent free end 76 is spaced downwardly from top 17 and is closer to bottom 19 of wall 24. In the lowered position, each inner end 84 adjacent bottom surface 102 abuts either central wall 42 or 44, which serves as a stop to prevent arm 78 from pivoting further downwardly about pivot 82. FIG. 4 shows that in the lowered position that each cup 14 is positioned mostly below bottom 19 of perimeter wall 24 with only a small portion of upper member 68 disposed thereabove.

In the raised view shown in FIG. 6, top surface 100 of each arm 78 is closely adjacent top 17 of perimeter wall 24 and is substantially horizontal. Bottom surface 102 angles upwardly and away from central wall 42 and 44 so that bottom surface 102 adjacent inner end 84 is closely adjacent bottom 19 of perimeter wall 24 and bottom surface 102 adjacent free end 76 is positioned upwardly of bottom 19 and closer to top 17 of wall 24. Preferably, inner end 84 of arm 78 adjacent top surface 102 abuts either central wall 42 or 44 to limit upward movement of arm 78 so that arm 78 remains within the vertical profile of perimeter wall 24. As FIG. 6 shows, most of each vacuum cup 14 is within the vertical profile of perimeter wall 24 and within the interior space defined within wall 24. More particularly, upper member 68 is disposed entirely within said vertical profile and only a portion of suction cup 72 extends downwardly of bottom 19 of wall 24.

The operation of cam bar 90 in moving pivot arms 78 and vacuum cups 18 from the lowered position to the raised position is best seen with reference to FIGS. 3, 5, 7 and 8. FIGS. 3 and 7 show ramps 86 of cam bar 90 positioned generally to the right of pivot arms 78 so that cam surfaces 88 are out of contact with cam followers 84 or so that a leading edge of cam surfaces 88 are barely in contact with cam followers 84 such that cam followers 84 rest on central walls 42 or 44 in the lowered position. In order to raise pivot arms 78 and vacuum cups 14, actuator 92 is operated to extend arm 96 which drives cam bar 90 longitudinally to the left as shown in the drawings so that ramps 86 slide within slots 45 (FIG. 1) and cam surfaces 88 slideably engage cam followers 84 so that the camming engagement therebetween causes pivot arms 78 to pivot about respective pivots 82 upwardly to the raised position (FIGS. 5, 8). The retraction of arm 96 of actuator 92 causes the reverse movement of cam bar 90 to allow pivot arms 78 to return to the lowered position. The force of gravity thus brings pivot arms 78 and vacuum cups 14 back to the lowered position although in a different orientation of lifter 10, pivot arms 78 may be spring biased to the lowered position if necessary.

Lifter 10 thus provides for a vacuum lifter which is mountable on the fork arms of a fork lift so that lifter 10 may be utilized in spaces for which its minimal profile offers significant advantage. Lifter 10 thus substantially reduces the amount of space or clearance above an object for insertion of lifter 10 to lift the object, which is particularly useful for the more efficient storage of sheet materials in a warehouse. More particularly, the fork lift driver will operate vacuum source 64 and actuator 92 in order to position vacuum cups 14 in a raised position to minimize the vertical profile of lifter 10 for insertion thereof into the space above an object such as sheet material. A remote control may be provided for this purpose if desired. Depending on the configuration of vacuum source 64 and its position, lifter 10 in its entirety may be inserted into relatively small clearance spaces above sheet material and the like. Even if vacuum source 64 is, for instance, seated atop of tubes 50 and 52 and extends upwardly beyond top 17 of perimeter wall 24, at least perimeter wall 24 in its entirety may be inserted into such a space. Once lifter 10 is positioned so that vacuum cups 14 are above the objects to be lifted, the operator then controls actuator 92 to lower vacuum cups 14 into contact with the upper surface of the object to be lifted, applies a vacuum via source 64 and conduits 66 to vacuum cups 14, and lifts the objects via the suction of cups 14 onto the object. As previously noted, perimeter wall 24 further provides protection to vacuum cups 14 particularly in the raised position and especially during movement of lifter 10 having a horizontal or lateral component.

In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.

Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described. 

1. An apparatus for lifting flat material comprising: a frame; a pair of fork lift arm receivers on the frame; and at least one vacuum cup mounted on and movable relative to the frame between raised and lowered positions.
 2. The apparatus of claim 1 further comprising an arm movably mounted on the frame and having a free end; and wherein the vacuum cup is mounted on the arm adjacent the free end.
 3. The apparatus of claim 1 further comprising an arm on the frame movable between raised and lowered positions; and wherein the frame has a top; a majority of the arm in its raised position is below the top of the frame; and the at least one vacuum cup is mounted on the arm.
 4. The apparatus of claim 3 wherein the frame has a bottom; and a majority of the arm in its lowered position is above the bottom of the frame.
 5. The apparatus of claim 1 further comprising an arm on the frame movable between raised and lowered positions; wherein the frame has a bottom; a majority of the arm in its lowered position is above the bottom of the frame; and the at least one vacuum cup is mounted on the arm.
 6. The apparatus of claim 1 further comprising first and second arms on the frame which are movable relative to the frame and one another; and wherein the at least one vacuum cup comprises first and second vacuum cups mounted respectively on the first and second arms.
 7. The apparatus of claim 6 further comprising first and second cam follower surfaces respectively on the first and second arms; and a cam engageable with the cam follower surfaces for respectively moving the arms.
 8. The apparatus of claim 1 further comprising a pivot arm having first and second ends; a pivotal connection between the pivot arm and the frame adjacent the first end of the pivot arm; a stop on the frame engageable with the first end of the pivot arm to limit its rotation about the pivotal connection; and wherein the at least one vacuum cup is mounted on the pivot arm adjacent the second end thereof.
 9. The apparatus of claim 1 further comprising a drive arm movable in a first direction; and wherein the at least one vacuum cup is movable between the raised and lowered positions in a second direction substantially perpendicular to the first direction in response to movement of the drive arm in the first direction.
 10. The apparatus of claim 9 further comprising a pivot arm having first and second ends; a pivotal connection between the pivot arm and the frame adjacent the first end of the pivot arm; and wherein the drive arm engages the pivot arm adjacent its first end; and the at least one vacuum cup is mounted on the pivot arm adjacent its second end.
 11. The apparatus of claim 1 further comprising a cam movably mounted on the frame; and wherein the at least one vacuum cup is movable between its raised and lowered positions in response to movement of the cam.
 12. The apparatus of claim 11 further comprising an arm on the frame; and a cam follower on the arm engageable with the cam; and wherein the at least one vacuum cup is mounted on the arm.
 13. The apparatus of claim 1 wherein the at least one vacuum cup has a downwardly-facing attaching surface which is generally horizontal in the raised and lowered positions.
 14. The apparatus of claim 1 wherein the frame comprises a wall which circumscribes the at least one vacuum cup.
 15. The apparatus of claim 14 wherein the wall circumscribes the at least one vacuum cup in the raised position.
 16. The apparatus of claim 1 wherein the at least one vacuum cup has a downwardly-facing attaching surface which is substantially horizontal; the frame comprises a protective wall having a top and a bottom; and the at least one vacuum cup comprises a portion between the top and bottom of the protective wall.
 17. The apparatus of claim 16 wherein the protective wall comprises a first wall forward of the at least one vacuum cup; a second wall rearward of the at least one vacuum cup; a third wall on one side of the at least one vacuum cup; and a fourth wall on a second side of the at least one vacuum cup opposite the first side.
 18. The apparatus of claim 16 wherein the fork lift arm receivers are between the top and bottom of the protective wall.
 19. The apparatus of claim 1 wherein the frame comprises a laterally extending perimeter wall defining therewithin an interior space and having a top and a bottom; and the at least one vacuum cup is in the interior space between the top and bottom of the perimeter wall.
 20. The apparatus of claim 1 wherein the frame has a top, a bottom, a front, a rear, and first and second sides extending from the front to the rear and defining therebetween a longitudinal direction; the frame comprises a longitudinally extending wall having a top and a bottom; and the at least one vacuum cup is between the top and bottom of and rearward of the longitudinally extending wall; and further comprising a rearwardly-facing entrance opening formed in each fork lift arm receiver adapted to receive therethrough a fork lift arm. 